Does all the technical jargon about digital video drive you bonkers?
Read on for a common sense explanation of digital video compression and codecs.
What is Digital Video Compression and Why Bother?
Without video compression, Internet video would simply not be possible. It’s that important.
Normally, video files are HUGE. Download times for raw, uncompressed video would be so high that no one would bother, even at broadband speeds.
Compression is the process of taking the huge raw file and knocking the file size down while preserving a decent picture.
Compression works by first analyzing the complex and detailed video signal. Portions of the signal not noticeable to the human eye are dropped. Detail and resolution are lost, but hopefully not too much. Different compression methods select differing data to lose, and this causes variable results.
When a video signal is compressed, when opened and played it is decompressed and some of the lost information is restored.
What is a Video Codec?
Codec is a term that combines the root words compression and decompression.
What is compressed must be decompressed.
To do so properly, requires the machine reading the file be able to reverse the process used for compression.
Hence, the two go together like a lock and key and form the word codec.
Compatibility issues come up with editing software or playing devices if the compression and decompression methods are incompatible.
This happens frequently and produces the joy known as the video maker’s headache. I don’t know any serious video maker who hasn’t struggled at one point with compression and file format incompatibility.
Different software platforms and the file formats they produce differ, in part, by their codecs. So if incompatibility arises, it almost always can be traced back to codecs.
Rarely do you need to concern yourself with the specifics of which codec is being used when, but being aware of compatibility issues can help you slog through whenever the inevitable problems arise.
For most of my digital video compression and conversion, I use the free software Handbrake and convert my finished video to MPEG4 before uploading it to the web. I usually bring it out of my editing program as a QuickTime (.mov).
Handbrake is easy to use, and MPEG4 is the most universally accepted format for the web today.
I hope this information helps you make better videos to share online.
Lorraine Grula
FOOD FOR THOUGHT
- True or False? Without video compression and decompression, internet video would not work! (True)
- In your own words, explain what the term “CODEC” means and how it was derived.
- Explain how the analogy with a lock and key pertains to video compression.
